A journalist photographs the new LG G2 smart phone in New York August 7, 2013.

The idea, playing off a slogan about LG's phone being "in the Cloud," was to fill up some helium balloons, with some of them containing a voucher for a free G2 smartphone inside. LG's Korea marketing team would then launch the balloons and see where they end up, once they lost their helium and drifted back to earth.

Anyone lucky enough to stumble upon a winning voucher could turn it in for a brand new phone. Presumably, this would launch a city-wide scavenger hunt, building hype for the brand.

So far, so good.

Local journalists were duly informed of the scheme, and invited to show up at the launching ground, at a park near Seoul's main river.

But to LG's surprise, a raft of non-journalists also showed up, having caught wind of the launch through the Internet or word of mouth. Their plan: to snare a balloon before it floated up too high into the sky.

And they came prepared, armed with BB guns and other improvised implements for snaring a balloon.

The moment the balloons were released, one LG employee recalls: "The crowd rushed to the balloons, running over other spectators in the process."

Contrary to some media coverage, nobody was shot or stabbed, says Kenneth Hong, the Seoul-based director of global communications for LG Electronics. "It was all minor scrapes and bruises," he says.

But why didn't LG shoo away the BB gun-wielding phone chasers, or at least keep them cordoned off from the balloon launchers? Mr. Hong, who was not involved in the event (responsibility for that fell to the domestic marketing staff), ventures a guess: "The event organizers would have needed a good reason to shoo people away. After all, it’s a public park, not private property. It isn’t illegal for people to stand around and watch, which is all they were doing."

So for the time being, LG is handling all the hospital bills and scrapping the rest of its planned balloon launches, which had been scheduled to take place at different venues around the country.

Instead, it's back to basics for the promotional campaign: a "street trends festival" on a hip shopping strip in Seoul's Gangnam district, and a video campaign on YouTube highlighting unique features of the phone.

Which is all straightforward enough, though perhaps lacking some of the interactiveness of the original plan.